The National League of Professional Baseball Clubs, known simply as the National League (NL), is the older of two leagues constituting Major League Baseball (MLB) in the United States and Canada, and the world's oldest current professional team sports league. Founded on February 2, 1876, to replace the National Association of Professional Base Ball Players, it is sometimes called the Senior Circuit, in contrast to MLB's other league, the American League, which was founded 25 years later. Both leagues currently have 15 teams. The two league champions of 1903 arranged to compete against each other in the inaugural World Series. After the 1904 champions failed to reach a similar agreement, the two leagues formalized the World Series as an arrangement between the leagues. National League teams have won 47 of the 110 World Series contested from 1903 to 2014.

By 1875, the National Association of Professional Base Ball Players was dangerously weak. The N.A. suffered from a lack of strong authority over clubs, unsupervised scheduling, unstable membership, dominance by one team (the Boston Red Stockings), and an extremely low entry fee ($10; about $193 in 2013 dollars, adjusted for inflation)[1] that gave clubs no incentive to abide by league rules when it was not convenient.

William Hulbert, a Chicago businessman and an officer of the Chicago White Stockings, approached several N.A. clubs with the plans for a league with stronger central authority and exclusive territories in larger cities only. Additionally, Hulbert had a problem—five of his star players were threatened with expulsion from the NAPBBP because Hulbert had signed them to his club using what were considered questionable means. Hulbert had a great vested interest in creating his own league. After recruiting St. Louis privately, four western clubs met in Louisville, Kentucky, in January 1876. With Hulbert speaking for the four in New York City on February 2, 1876, the National League was established with eight charter members, as follows:[2]

Louisville Grays, a new franchise (folded after the 1877 season when four players were banned for gambling)

The National League's formation meant the end of the N.A., as its remaining clubs shut down or reverted to amateur or minor status. The only strong club from 1875 excluded in 1876 was a second one in Philadelphia, often called the White Stockings or Phillies.

The first game in National League history was played on April 22, 1876, at Philadelphia's Jefferson Street Grounds, 25th & Jefferson, between the Philadelphia Athletics and the Boston baseball club. Boston won the game 6–5.

The new league's authority was tested after the first season. The Athletic and Mutual clubs fell behind in the standings and refused to make western road trips late in the season, preferring to play games against local non-league competition to recoup some of their losses rather than travel extensively. Hulbert reacted to the clubs' defiance by expelling them, an act which not only shocked baseball followers (New York and Philadelphia were the two most populous cities in the league) but made it clear to clubs that league schedule commitments, a cornerstone of competition integrity, were not to be ignored.

The National League operated with six clubs during 1877 and 1878. Over the next several years, various teams joined and left the struggling league. By 1880, six of the eight charter members had folded. The two remaining original NL franchises, Boston and Chicago, remain in operation today as the Atlanta Braves and the Chicago Cubs. When all eight participants for 1881 returned for 1882—the first off-season without turnover in membership—the "circuit" consisted of a zig-zag line connecting the eight cities: Chicago, Detroit, Cleveland, Buffalo, Troy (near Albany), Worcester, Boston, and Providence.

In 1883 the New York Gothams and Philadelphia Phillies began National League play. Both teams remain in the NL today, the Phillies in their original city and the Gothams (later renamed Giants) now in San Francisco.

The NL encountered its first strong rival organization when the American Association began play in 1882. The A.A. played in cities where the NL did not have teams, offered Sunday games and alcoholic beverages in locales where permitted, and sold cheaper tickets everywhere (25 cents versus the NL's standard 50 cents, a hefty sum for many in 1882).

The National League and the American Association participated in a version of the World Series seven times during their ten-year coexistence. These contests were less organized than the modern Series, lasting as few as three games and as many as fifteen, with two Series (1885 and 1890) ending in disputed ties. The NL won four times and the A.A. only once, in 1886.

Starting with the Pittsburgh Pirates in 1887, the National League began to raid the American Association for franchises to replace NL teams that folded. This undercut the stability of the A.A.

Other new leagues that rose to compete with the National League were the Union Association and the Players League. The Union Association was established in 1884 and folded after playing only one season, its league champion St. Louis Maroons joining the NL. The Players' League was established by the Brotherhood of Professional Base-Ball Players, the sport's first players' union, which had failed to persuade the NL to modify its labor practices, including a salary cap and a reserve clause that bound players to their teams indefinitely. The NL suffered many defections of star players to the Players' League, but the P.L. collapsed after one season. The Brooklyn, Chicago, Pittsburgh, and New York franchises of the NL absorbed their Players' League counterparts.

The labor strife of 1890 hastened the downfall of the American Association. After the 1891 season, the A.A. disbanded and merged with the NL, which became known legally for the next decade as the "National League and American Association". The teams now known as the Cincinnati Reds, Los Angeles Dodgers (originally Brooklyn) and Pittsburgh Pirates (as well as the now-defunct Cleveland Spiders) had already switched from the A.A. to the NL prior to 1892. With the merger, the NL absorbed the St. Louis Browns (now known as the St. Louis Cardinals), along with three other teams that did not survive into the 20th century (for those three teams, see "Partnership with the American League"). While four teams that moved from the A.A. remain in the NL today (Pittsburgh [1887], Cincinnati [1890], Los Angeles [originally Brooklyn; 1890], and St. Louis [1892]), only two original NL franchises (1876) remain in the league: the Chicago Cubs and the Atlanta Braves (originally in Boston, and later Milwaukee). The Cubs are the only charter member to play continuously in the same city. The other two pre-1892 teams still in the league are the Philadelphia Phillies and the San Francisco Giants (originally New York), both of which joined in 1883.

The National League became a 12-team circuit with monopoly status for the rest of the decade. The league became embroiled in numerous internal conflicts, not the least of which was a plan supported by some owners (and bitterly opposed by others) to form a "trust," wherein there would be one common ownership of all twelve teams. The NL used its monopsony power to force a $2,400 limit on annual player wages in 1894.

As the 20th century dawned, the NL was in trouble. Conduct among players was poor, and fistfights were a common sight at games. In addition to fighting each other, they fought with the umpires and often filled the air at games with foul language and obscenities. A game between the Orioles and Boston Beaneaters (a precursor to today's Atlanta Braves) in 1894 ended up having tragic consequences when players became engaged in a brawl and several boys in the stands started a fire. The blaze quickly got out of hand and swept through downtown Boston, destroying or damaging 100 buildings. Team owners argued with each other and players hated the NL's $2,400 salary cap. Many teams also ran into trouble with city governments that forbade recreational activities on Sunday.

Billy Sunday, a prominent outfielder in the 1880s, became so disgusted with the behavior of teammates that he quit playing in 1891 to become one of America's most famous evangelical Christian preachers. Most fans appear to have felt the same way, because attendance at games was plummeting by 1900.

After eight seasons as a 12-team league, the NL contracted back to eight teams for the 1900 season, eliminating its teams in Baltimore, Cleveland, Louisville (which has never had another major league team since), and Washington. This provided an opportunity for competition. Three of those cities received franchises in the new American League (AL) when the AL opened for business in 1900, with the approval of the NL, which regarded the AL as a lesser league. The AL declined to renew its National Agreement membership when it expired, and on January 28, 1901, the AL officially declared itself a second major league in competition with the NL. By 1903, the upstart AL had placed new teams in the National League cities of Boston, Chicago, New York, Philadelphia, and St. Louis. Only the Cincinnati Reds and Pittsburgh Pirates had no AL team in their markets. The AL among other things enforced a strict conduct policy among its players.

The National League at first refused to recognize the new league, but reality set in as talent and money was split between the two leagues diluting the league and less financial success. After two years of bitter contention, a new version of the National Agreement was signed in 1903. This meant formal acceptance of each league by the other as an equal partner in major-league baseball, mutual respect of player contracts, and an agreement to play a postseason championship—the World Series.

Major League Baseball narrowly averted radical reorganization in November 1920. Dissatisfied with American League President and National Commission head Ban Johnson, NL owners dissolved the league on November 8 during heated talks on MLB reorganization in the wake of the Black Sox Scandal. Simultaneously, three AL teams also hostile to Johnson (Boston Red Sox, Chicago White Sox, and New York Yankees) withdrew from the AL and joined the eight NL teams in forming a new National League; the 12th team would be whichever of the remaining five AL teams loyal to Johnson first chose to join; if none did so an expansion team would have been placed in Detroit, by far the largest one-team city at that time. Four days later, on November 12, both sides met (without Johnson) and agreed to restore the two leagues and replace the ineffective National Commission with a one-man Commissioner in the person of federal Judge Kenesaw Mountain Landis.[3]

In 1969, as a result of its expansion to 12 teams, the National League—which for its first 93 years had competed equally in a single grouping—was reorganized into two divisions of six teams (respectively named the National League East and West, although geographically it was more like North and South), with the division champions meeting in the National League Championship Series (an additional round of postseason competition) for the right to advance to the World Series.

In 1993 the league expanded to 14 teams, adding the Colorado Rockies and the Florida Marlins (which became the Miami Marlins shortly after the end of the 2011 season). In 1998, the Arizona Diamondbacks became the league's fifteenth franchise, and the Milwaukee Brewers moved from the AL to the NL, giving the NL 16 teams for the next 15 seasons.

In 1994, the league was again reorganized, into three geographical divisions (East, West and Central, all currently with five teams; from 1994–97 the West had one fewer team, and from 1998–2012, the Central had one more team). A third postseason round was added at the same time: the three division champions plus a wild card team (the team with the best record among those finishing in second place) now advance to the preliminary National League Division Series. Due to a players' strike, however, the postseason was not actually held in 1994.

Before the 1998 season, the American League and the National League each added a fifteenth team. Because of the odd number of teams, only seven games could possibly be scheduled in each league on any given day. Thus, one team in each league would have to be idle on any given day. This would have made it difficult for scheduling, in terms of travel days and the need to end the season before October. In order for MLB officials to continue primarily intraleague play, both leagues would need to carry an even number of teams, so the decision was made to move one club from the AL Central to the NL Central. Eventually, Milwaukee agreed to change leagues.[4]

Often characterized as being a more "traditional" or "pure" league, the National League never adopted the designated hitter rule that was adopted by the American League in 1973. In theory, this means the role of the manager is greater in the National League than in the American, because the NL manager must take offense into account when making pitching substitutions and vice versa. However, this is disputed by some, such as former Detroit Tigers manager Jim Leyland, who claims the American League is more difficult because AL managers are required to know exactly when to pull a pitcher, where an NL manager merely pulls his pitcher when that spot comes up in the batting order. Overall, there are fewer home runs and runs scored in the National League than in the American, due to the presence of the pitcher in the NL batting order.

For the first 96 years of its coexistence with the American League, National League teams faced their AL counterparts only in exhibition games or in the World Series. Beginning in 1997, however, interleague games have been played during the regular season and count in the standings. As part of the agreement instituting interleague play, the American League's designated-hitter rule is used only in games where the American League team is the home team.

In the 1990s, the offices of American League and National League presidents were discontinued. Additionally, the distinction between AL and NL umpires was erased, and instead all umpires were unified under MLB control. With these actions, as well as the institution of interleague play, little remains to differentiate between the two leagues other than the use of the DH in the AL and tradition.

By 2011, MLB had changed its policy on interleague play, deciding to have interleague games throughout the season. This policy would allow each league to have 15 teams, with one team in each league playing an interleague game on any given day. As a condition of the sale of the Astros to Jim Crane in November 2011, the team agreed to move to the American League effective with the 2013 season.[5]

Through the 2014 season, the Giants have won the most NL pennants with 23. Representing the National League against the American, the Cardinals have won the most World Series (11) followed by the Giants (8), Dodgers (6), Pirates (5), and Reds (5). St. Louis also holds the distinction of being the only A.A. club to defeat an NL club in the 19th-century version of the World Series.

1998: Milwaukee Brewers transfer from the American League. (Before the 1998 season, the American League and the National League each added a fifteenth team. Because of the odd number of teams, only seven games could possibly be scheduled in each league on any given day. Thus, one team in each league would have to be idle on any given day, or there would have be at least one interleague game almost every day. This would have made it difficult for scheduling. To avoid this problem, Milwaukee agreed to change leagues.)

Shea Stadium prior to the start of a New York Mets game in 2008. Shea had the best attendance in the National League that year, garnering over 53,000 fans per game on average.

Atlanta Braves, the oldest continually operating team in Major League Baseball; enfranchised in 1871 as the Boston Red Stockings (or Red Caps) in National Association, and with connections to the original independent professional Cincinnati Red Stockings of 1869–70; joined National League as charter member (1876). Known as "Beaneaters" and other nicknames, as original nickname faded and became re-associated with Cincinnati (and later with the Boston Red Sox). Adopted nickname "Braves" in 1912. Moved to Milwaukee (1953) and to Atlanta (1966). Prior to the 1994 realignment, the Braves competed in the West division.

Philadelphia Phillies, enfranchised 1883 as the Quakers and adopted the Phillies name officially in 1884. From 1943 through 1948, the Phillies unofficially changed their name to the "Philadelphia Blue Jays." Although their jerseys retained the name "Phillies", they wore a blue-jay patch on their sleeve. The team is the oldest continuous, one-name, one-city franchise in American professional sports history.[10]

Chicago Cubs enfranchised 1870 as an independent professional, chartered into the National Association in 1871, but suspended operations for 1872 and 1873 following the Great Chicago Fire. The team has been continuously active since 1874, making it the oldest continuously active team in its original city in Major League Baseball. It joined National League as charter member (1876). Originally called "Chicago White Stockings" and later "Chicago Colts" and several other names, first called "Cubs" in 1902.

Cincinnati Reds enfranchised 1882 in American Association, joined National League (1890).

Milwaukee Brewers enfranchised 1969 as the Seattle Pilots in American League, moved to Milwaukee (1970), transferred to National League (1998).

Pittsburgh Pirates enfranchised 1882 in American Association, joined National League (1887).

Los Angeles Dodgers enfranchised 1883 as a minor league team, entered into the American Association as the Brooklyn Atlantics in 1884, soon acquired nickname "Dodgers" (from "trolley dodgers"), joined National League (1890). Also dubbed "Bridegrooms", "Superbas", and "Robins" at various times, in addition to "Dodgers". Moved to Los Angeles (1958)